Dwain Chambers was banned from athletics for two years in 2003 after testing positive for the anabolic steroid THG. Photograph: Stephen Hird/Reuters

This weekend's Olympic trials in Birmingham have been thrown into selection confusion after the decision in the high court yesterday to postpone Dwain Chambers' legal challenge to run in Beijing.

UK Athletics is faced with the prospect of not naming any 100m runners for the Games until the last possible moment because of the indecision that remains over whether Chambers will be among them. Even if the controversial sprinter wins the 100m final on Saturday to earn selection he will remain ineligible to compete because of his ban by the British Olympic Association after his positive drugs test in 2003. Chambers now hopes to secure an injunction next week to allow him to race in Beijing.

The 30-year-old runner was in court yesterday when the BOA achieved its first objective of preventing a hearing tomorrow, over the validity of its bylaw, that would have decided the Olympic future of the former European 100m champion. It wanted more time to prepare its case.

However, Chambers was granted an injunction hearing next Wednesday when his legal team will seek a temporary lifting of the bylaw which bans drugs cheats from ever representing Great Britain at the Games, enabling him to compete in Beijing next month. A full legal test is planned for next year but if he succeeds with this injunction it could leave the bylaw open to further challenges from drug cheats.

The BOA has to notify the International Olympic Committee of its complete team on Sunday week. Although UK Athletics will name its first wave of selections on Monday, the blue-ribbon event of the trials has left it with a selection nightmare over what to do with its other leading sprinters should Chambers win. He is the favourite to do so after topping the British 100m rankings this summer.

UK Athletics hopes to take three 100m men to the Olympics - normally the first three in the trials. It is undecided whether to discard a Chambers victory on Saturday and pick the next three, if they have met the qualifying standard, knowing it would then have to let one of them down if the Londoner won his injunction.

Alternatively, it may pick two but leave one in limbo until the Chambers case is finished. Another scenario is picking no one for the 100m and waiting until the result of the court case. Tyrone Edgar, Harry Aikines-Aryeetey, Marlon Devonish, Rikki Fifton, Simeon Williamson and Craig Pickering all have the qualifying time.

The trials at the Alexander Stadium open with the heats of the 100m tomorrow. Had the initial hearing taken place earlier that day, Chambers might have known by then whether he was clear for Beijing. But his legal team were happy with the decision of Justice Sir Colin Mackay yesterday. Both parties will supply further written evidence before the injunction hearing.

Nick Collins, Chambers' solicitor, said: "We are delighted it is going to take place next Wednesday in advance of the Games and we will of course respect and abide by the court's decision."

Chambers said: "Friday and Saturday, that's where the job really matters. I am confident about what I am capable of doing at my end, which is to cross the line first, and the rest will be left up to the decision which will be made next Wednesday.

"It was pretty tough in there this morning but this is a scenario I am not familiar with. It will be good, it will be fine."

Lord Colin Moynihan, the chairman of the BOA, said: "The BOA strongly welcome the fact that we will have a full hearing now along the lines that we have applied to the court for. We will continue with that hearing to vigorously defend the bylaw and to now bring the witnesses that we wanted to bring and the cross-examination that is necessary to defend the bylaw.

"The principle outcome today is something that we warmly welcome ... we will equally strongly resist that injunction on the same principle of the defence of the bylaw."

Chambers was banned for two years after testing positive for the anabolic steroid tetrahydrogestrinone. His legal team argues that the BOA's bylaw is "inherently unfair" and an unreasonable "restraint of trade". Chambers is the first athlete to challenge the bylaw legally and the BOA will seek to make legal play of the fact that it has taken him more than two years since he was allowed back to bring this case.